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Snow, dry air, and wind dominate April

April 24, 2015

Snowfall followed by dry air:

Many places around the state reported at least a trace of
snow on April 21st (Tuesday) and 22nd (Wednesday), and some places reported
measurable amounts. The following were new daily record snowfalls amounts
for April 21st:
4.0" at Isabella
1.5" at Embarrass, Kabetogama, and Ely

In addition Orr reported 3.0", Tower 2.0", and International Falls
1.9" but these were not new record totals for the date. Following
the snow, the low temperature plunged to just 10°F at both Fosston and
Embarrass, the coldest reading in the nation for April 23rd. The snowfall
rapidly melted due to temperatures rebounding closer to normal following the
cold snap of April 20-23. The temperature climbed all the way to 63°F at Luverne on Thursday. Elsewhere temperatures climbed into the 50s F on Thursday
(April 23), with unusually dry air. In fact MSP set a new low dew point
record for April 23 with an afternoon reading of just 1F, and a relative
humidity of 12 percent, drier than Phoenix, AZ on Thursday!

Windy April:

As we have reported before, April is generally the windiest
month of the year based on climate history from most Minnesota
communities. But, April of this year has been particularly windy, with
average wind speeds above the historical average, as well as a high frequency
of wind gusts over 30 mph. Here is a list of average wind speeds and
frequency of gusts over 30 mph for selected cities across the state:
Location Ave Wind Speed for April
2015 Number of days wind has gusted above
30mph
MSP
12.3
mph
9 days (peak of 46 mph on the 2nd)
Rochester 14.4 mph
14 days (peak of 47 mph on the 1st)
St
Cloud
11.5
mph
8 days (peak of 49 mph on the 2nd)
Duluth
12.4
mph
10 days (peak of 58 mph on the 2nd)
International Falls 9.2
mph
5 days (peak of 43 mph on the 13th)
Alexandria
14.1
mph
12 days (peak of 49 mph on the 2nd)
Redwood
Falls 12.8
mph
16 days (peak of 55 mph on the 1st)
Mankato
13.9
mph
15 days (peak of 45 mph on the 1st)
Fargo-Moorhead 14.3
mph
12 days (peak of 54 mph on the 2nd)
Hallock
13.1 mph
11 days (peak of 62 mph on the 15th)
Crookston
14.0
mph
11 days (peak of 47 mph on the 13th)
Morris
14.5
mph
15 days (peak of 52 mph on the 13th)
Worthington
14.6
mph
14 days (peak of 48 mph on the 1st)

As a result of the windy month many weather observers as well as farmers have
reported seeing blown soil accumulate in drainage ditches across the rural landscape.
Hopefully winds will diminish for the peak of the crop planting season which is
coming up soon.

Weekly Weather Potpourri:

NOAA announced this week that March 2015 was the warmest globally over the period 1880-present. In addition they announced that the first 3-months of 2015 were also the warmest of record since 1880, surpassing the previous warmest 3-month start to the year back in 2002. You may want to catch up on other highlights in the NOAA-NCDC article.

NOAA also announced this week a tool to examine and track
the tropical storm activity in the Western Pacific Ocean. This tool also
provides sea surface temperature analysis and rainfall forecasts across the
Pacific Basin.It is
hosted on the web site at NOAA-CPC.

Tornado news of the week included:

A
tornado ripped through the city of Xanxere, Santa Catarina in southern Brazil
this week killing two people, injuring over 100 and causing quite a bit of
destruction. Winds associated with the tornado were estimated to be over
120 mph. Also on Tuesday of this week (April 21st) two unusual tornadoes
were reported to have briefly touched down in Riverside County,
California. Fortunately little damage was reported.

MPR listener question:

We live around Lake Nokomis and listen to you and Cathy every Friday, and remember earlier this spring you told us how infrequent periods of calm with no wind are in the Twin Cities. It seems like the wind has been a constant this month. Have we had any periods of calm winds (speed less than 1 mph) so far?

Answer:

Indeed using the hourly climate data from MSP Airport I find only 15 hours with calm winds so far this month (through the 24th). That is roughly just 2 percent of the time and most of those hours were between midnight and 6 am, not to be witnessed by many citizens. So, indeed significant wind has been a constant this month in our Minnesota climate signature.

Twin Cities Almanac for April 24th:

The average MSP high temperature for this date is 60 degrees
F (plus or minus 11 degrees F standard deviation), while the average low is 41
degrees F (plus or minus 9 degrees F standard deviation).

Average dew point for April 24th is 35 degrees F, with a maximum of 66 degrees
F in 1948 and a minimum of 8 degrees F in 1918.

All-Time state records for April 24th:

The state record high temperature for this date is 92 degrees F at Milan (Chippewa County) and Madison (Lac Qui Parle County) in 1962, and again at Montevideo (Chippewa County) in 2009. The state record low temperature for this date is 3 degrees F at Sawbill Camp (Cook County) in 1936. State record precipitation for this date is 5.44 inches at Winona Dam (Winona County) in 1990; and the state record snowfall for this date is 15.0 inches at Fosston (Polk County) in 1937.

Past Weather Features:

The coldest April 24th occurred in 1956 when morning low
temperatures dropped into the teens F, not just in northern Minnesota but
across all reaches of the state. As far south as Preston it was just 15°F,
while Rochester reported 17°F. After starting the day at 13°F Little Falls
warmed up to an afternoon high of 58°F.

April 24-25, 1962 brought a dose of mid-summer temperatures to the state as
over 80 Minnesota cities reported daytime highs in the 80s F. Itasca
State Park soared to 88°F while over two dozen southern Minnesota climate
observers reported daytime highs of 90°F or higher. The heat spell was
short-lived as frost occurred in many areas of the state by the morning
of April 29th.

A winter storm brought heavy snow to northern Minnesota counties over April
23-24, 1968. Many observers reported 5 to 10 inches of snowfall. Some
north shore observers along Lake Superior received 12 to 15 inches of
snow. The storm brought winds of over 40 mph which caused numerous power
outages. The Duluth and Hibbing Airports were closed for a time due to
the heavy snow and poor visibility.

Strong thunderstorms developed over south-central and southeastern Minnesota
late on the evening of April 23, 1990 and carried over into the early morning
of April 24th. Heavy rains and hail fell in many areas with rainfall
amounts commonly ranging from 3 to 4 inches. Rochester, Grand Meadow, and
Red Wing reported over 4 inches of rain, while Winona Dam reported over 5
inches. The heavy rains broad flooding to the Cedar and Root
Rivers. A number of homes in Austin reported flooded basements.

Outlook:

Somewhat cooler than normal temperatures on Saturday with a chance for showers early in the day, especially in the south and east. Warming trend starts on Sunday with drier weather. Temperatures should be above normal most of next week and it will be mostly dry.